Antibiotic and fermentation process of preparing

ABSTRACT

Novel antibiotic U-59,761 producible in a fermentation under controlled conditions using a biologically pure culture of the microorganism Saccharopolyspora hirsuta strain 367, NRRL 12045. This antibiotic is active against various microorganisms, for example, Staphylococcus aureus, Streptococcus pyogenes, Sarcina lutea, Klebsiella pneumoniae, Mycobacterium avium, and Bacteroides fragilis. Thus, antibiotic U-59,761 can be used in various environments to eradicate or control such bacteria.

BRIEF SUMMARY OF THE INVENTION

Antibiotic U-59,761 is producible in a fermentation under controlled conditions using a biologically pure culture of the new microorganism Saccharopolyspora hirsuta strain 367, NRRL 12045.

Antibiotic U-59,761 is active against various bacteria. Thus, this antibiotic can be used to disinfect washed and stacked food utensils contaminated with S. aureus. Since antibiotic U-59,761 is active against Mycobacterium avium, it can be used in birds and rabbits to control this organism which is a known producer of generalized tuberculosis in these animals. Further, antibiotic U-59,761 can be used as a bacteriostatic rinse for laundered clothes, and for impregnating papers and fabrics; and, it is also useful for suppressing the growth of sensitive organisms in plate assays and microbiological media.

DETAILED DESCRIPTION OF THE INVENTION Chemical and Physical Properties of Antibiotic U-59,761

Molecular Weight: 422.2269 (mass spectrometry).

Molecular Formula: C₂₃ H₃₄ O₇

Elemental Analysis: C, 65.63; H, 7.97.

Optical Rotation: [α]_(D) ²⁵ +121° (C, 0.7575 MeOH).

Ultraviolet Absorption: End absorption only.

Solubilities: Soluble in methanol and ethanol; less soluble in methyl chloride and methylene chloride; relatively insoluble in petroleum ether and cyclohexane.

Melting Point: 201°-206° C.

Infrared Absorption Spectrum:

Antibiotic U-59,761 has a characteristic infrared absorption spectrum in a mineral oil mull as shown in the drawing FIG. 1. Peaks are observed at the following wave lengths expressed in reciprocal centimeters:

    ______________________________________                                         Band Frequency                                                                 (Wave numbers         Intensity                                                ______________________________________                                         3415                  S                                                        3290                  M, sh.                                                   3069                  W                                                        3042                  W                                                        2990                  M                                                        2960                  S                                                        2925                  S                                                        2872                  S                                                        2854                  S                                                        2824                  M                                                        2724                  W                                                        2652                  W                                                        1701                  S                                                        1651                  W                                                        1465                  M, sh.                                                   1453                  S                                                        1421                  W                                                        1376                  M                                                        1366                  M                                                        1349                  M                                                        1335                  M                                                        1328                  M                                                        1314                  M                                                        1295                  S                                                        1273                  M                                                        1250                  M                                                        1239                  M                                                        1231                  M                                                        1213                  W                                                        1190                  W                                                        1183                  W                                                        1168                  W                                                        1153                  M                                                        1139                  W                                                        1124                  M                                                        1111                  S                                                        1104                  S                                                        1089                  M                                                        1079                  M                                                        1057                  M                                                        1029                  S                                                        1017                  S                                                        1002                  M                                                        990                   S                                                        970                   M                                                        961                   M                                                        950                   M                                                        937                   M                                                        928                   W                                                        907                   W                                                        887                   M                                                        879                   M                                                        875                   W                                                        856                   W                                                        820                   W                                                        796                   W                                                        781                   W                                                        758                   M                                                        717                   M                                                        687                   W                                                        660                   M                                                        648                   M                                                        631                   M                                                        ______________________________________                                          Key:                                                                           S=Strong, M=Medium, W=Weak, sh.=shoulder                                 

¹³ C-Nuclear Magnetic Resonance (NMR) Spectrum: Antibiotic U-59,761 has a characteristic ¹³ C-NMR spectrum as shown in FIG. 2 of the drawing.

Antimicrobial spectrum of antibiotic U-59,761: Antibiotic U-59,761 is active against various microorganisms as shown in the following tables:

    ______________________________________                                         Agar Diffusion                                                                                       Inhibition Zone                                          Organism              Size (mm).sup.1                                          ______________________________________                                         B. subtilis UC 564    0                                                        B. subtilis UC 6033   0                                                        S. aureus UC 70       trace                                                    S. aureus UC 3665     17                                                       S. aureus UC 6029     trace                                                    S. lutea UC 130       35                                                       S. lutea UC 3383      34                                                       S. lutea sens         38                                                       K. pneumoniae UC 58   27                                                       E. coli UC 51         0                                                        S. schottmuelleri UC 126                                                                             0                                                        P. vulgaris UC 93     0                                                        P. aeruginosa UC 95   0                                                        M. avium UC 159       26                                                       P. oxalicum UC 1268   0                                                        S. pastorianus UC 1342                                                                               0                                                        R. sphaeroides UC 3238                                                                               20                                                       S. pyogenes UC 6055   0                                                        B. fragilis UC 6513   33                                                       C. perfringens UC 6509                                                                               33                                                       ______________________________________                                          .sup.1 Schleicher and Schuell Inc., 704 paper discs (12.7 mm) dipped in 1      mg/ml methanolic solution of antibiotic, dried, and applied to seeded aga      trays. Inhibition zone read after 16 hr incubation.                      

A solution of Antibiotic U-59,761 was prepared in ethanol, diluted in BHI broth (Difco), and MIC's were determined using the standard microplate broth-dilution method.

    ______________________________________                                                                 Minimal Inhibitory                                     Organism       UC       Concentration (μg/ml)                               ______________________________________                                         S. aureus      75       125                                                                   570      125                                                                   746      250                                                    S. fecalis     694      >1000                                                  S. pyogenes    152      500                                                    D. pneumoniae  41       1000                                                   E. coli        45       1000                                                   K. pneumoniae  58       1000                                                   P. vulgaris    93       >1000                                                  Ps. aeruginosa 95       >1000                                                  S. schottmuelleri                                                                             126      1000                                                   ______________________________________                                          "UC" is a registered trademark of The Upjohn Company culture collection.       These cultures can be obtained from The Upjohn Company, Kalamazoo,             Michigan upon request.                                                   

THE MICROORGANISM

The microorganism used for the production of antibiotic U-59,761, as described herein, is a biologically pure culture of Saccharopolyspora hirsuta strain 367, NRRL 12045.

A subculture of this microorganism can be obtained from the permanent collection of the Northern Regional Research Laboratory, U.S. Department of Agriculture. Peoria, Ill., U.S.A. Its accession number in this depository is NRRL 12045. It should be understood that the availability of the culture does not constitute a license to practice the subject invention in derogation of patent rights granted with the subject instrument by governmental action.

The microorganism of this invention was studied and characterized by Alma Dietz and Grace P. Li of The Upjohn Company Research Laboratories.

An actinomycete isolated in the Upjohn soils screening laboratory has been characterized and found to have the macroscopic, microscopic and whole cell hydrolysate properties of the genus Saccharopolyspora [Iwasaki, A., N. Itoh, and T. Mori, 1979. A new broad-spectrum aminoglycoside antibiotic complex, sporaricin. II. Taxonomic studies on the sporaricin producing strain Saccharopolyspora hirsuta subsp. kobensis nov. subsp. J. Antibiotics. 32: 180-186.][Lacey, J. and M. Goodfellow. 1975. A novel actinomycete from sugar-cane bagasse: Saccharopolyspora hirsuta gen. et sp. nov. J. Gen. Microbiol 88:75-85]. A comparison with the type culture Saccharopolyspora hirsuta ATCC 27875 is given in Tables 1 and 2. A comparison with the type culture and with the subspecies, Saccharopolyspora hirsuta ss. kobensis ATCC 20501 [Iwasaki, A. supra] based on data published for these strains is given in Table 3.

Unique properties of the genus Saccharopolyspora are its butyrous or gelatinous-type vegetative growth, sparse aerial growth which is best studied after 21 days incubation, yellow to orange to orange-tan vegetative growth and pigment production, spore chains developing in a sheath with unique hair tufts with truncated bases and smooth areas between the tufts, the presence of meso-diaminopimelic acid, arabinose and galactose in whole cell hydrolysates and in cell wall preparations. L-diaminopimelic acid was detected in addition to meso-DAP in our cell wall preparations.

No antibiotic production has been reported for the type culture; the subspecies kobensis produces the antibiotic complex sporaricin (KA-6606) [Iwasaki, A. supra]. The new isolate is distinguished by the production of antibiotic U-59,760. The only significant difference among the strains is in their antibiotic production capability. Therefore, the new strain is designated Saccharopolyspora hirsuta strain 367. The taxonomic methods used herein were those cited in Dietz [Dietz, A. 1954. Ektachrome transparencies as aids in actinomycete classification. Ann N. Y. Acad. Sci. 60: 152-154.] [Dietz, A. 1967. Steptomyces steffisburgensis sp. n. J. Bacteriol. 94: 2022-2026.], Dietz and Mathews [Dietz, A., and J. Mathews. 1971. Classification of Streptomyces spore surfaces into five groups. Appl. Microbiol. 21: 527-533.], Becker et al. [Becker, B., M. P. Lechevalier, and H. A. Lechevalier. 1966. Chemical composition of cell wall preparations from strains of various form-genera of aerobic actinomycetes. Appl. Microbiol. 13 236-243.], Lechevalier and Lechevalier [Lechevalier, H. A., and M. P. Lechevalier. 1970. A critical evaluation of the genera of aerobic actinomycetes, p. 393-405. In H. Prauser (ed.), The Actinomycetales. Gustav Fisher, Jena.] [Lechevalier, M. P., and H. A. Lechevalier. 1970. Chemical composition as a criterion in the classification of aerobic antinomycetes. Int. J. Syst. Bacteriol. 20: 435-443.], and Shirling and Gottlieb [Shirling, E. B., and D. Gottlieb. 1966. Methods for characterization of Streptomyces species. Int. J. Syst. Bacteriol. 16: 313-340.]. Color characteristics: Aerial mycelium gray to gray-pink (very sparse at 14 days). Melanin negative. Appearance on Ektachrome is given in Table 1. Surface colors of the vegetative growth were determined to be red (R) or yellow (Y) by matching the color with the chips in the Tresner and Backus [Tresner, H. D., and E. J. Backus. 1963. System of color wheels for streptomycete taxonomy. Appl. Microbiol. 11: 335-338.] color wheels.

Microscopic characteristics: Spore masses and spore chains, intact and fragmented, and flexuous or loosely spiraled chains, as observed by Scanning Electron Microscopy, appear to develop in a sheath which is at first almost smooth; then unique tufts of hairs (triangular at the base) are formed. The surface between the tufts is smooth. Finally, the sheath becomes covered with fine long hairs. The long sheaths are tangled and appear to arise from, or fuse to form pseudosporangia. As the chains come in contact with the substrate the spores become smooth in outline with a depressed or ridged appearance. "Empty" hyphae are noted in the developed chains. Microscopic characteristics are best noted after 21 days incubation at 28°-37° C. Nocardioform fragmentation may be seen in 21 day cultures.

Growth on carbon compounds: Under the test conditions of Shirling and Gottlieb [supra] growth was good on the positive control (basal medium plus D-glucose), sucrose, D-mannitol, D-fructose and raffinose. Growth was doubtful on L-arabinose and D-xylose. There was no growth on the negative control (basal medium only), inositol, rhamnose, and cellulose.

Whole cell analysis: meso-Diaminopimelic acid, arabinose and galactose were detected.

Cell wall analysis: meso-Diaminopimelic acid, L-diaminopimelic acid, arabinose and galactose were found.

Cultural and biochemical characteristics: See Table 2.

Temperature: There was no to very poor growth at 18° C. on Bennett's and maltose-tryptone agars and poor growth on Czapek's sucrose agar. Growth was good at 24°-45° C. There was no growth at 55° C.

                                      TABLE 1                                      __________________________________________________________________________     Color characteristics* of Saccharopolyspora hirsuta ATCC 27875 and S.          hirsuta strain 367 on                                                          Ektachrome                                                                                      S. hirsuta ATCC 27875                                                                         S. hirsuta strain 367                          Agar Medium                                                                             Determination                                                                          Chip                                                                              Color       Chip                                                                              Color                                       __________________________________________________________________________     Bennett's                                                                               S       71 moderate orange yellow                                                                     71 moderate orange yellow                               R       71 moderate orange yellow                                                                     71 moderate orange yellow                      Czapek's sucrose                                                                        S       74 strong yellowish brown                                                                     67 brilliant orange yellow                              R       72 dark orange yellow                                                                         67 brilliant orange yellow                     Maltose-tryptone                                                                        S       71 moderate orange yellow                                                                     71 moderate orange yellow                               R       71 moderate orange yellow                                                                     71 moderate orange yellow                      Peptone-iron                                                                            S       68 strong orange yellow                                                                       68 strong orange yellow                                 R       68 strong orange yellow                                                                       68 strong orange yellow                        0.1% Tyrosine                                                                           S       73 pale orange yellow                                                                         71 moderate orange yellow                               R       73 pale orange yellow                                                                         71 moderate orange yellow                      Casein   S       73 pale orange yellow                                                                         70 light orange yellow                                  R       73 pale orange yellow                                                                         73 pale orange yellow                          __________________________________________________________________________      *Color was determined by comparison with NBS color chips (SP 440. Color:       Universal Language and Dictionary of Names. U.S. Government Printing           Office, Washington, DC 20402. SRM 2106. ISCCNBS Centroid Color Charts.         Office of Standard Reference Material, Room B311, Chem. Building, Nationa      Bureau of Standards, Washington, DC 20234. S = Surface R = Reverse       

                                      TABLE 2                                      __________________________________________________________________________     Cultural and biochemical characteristics of Saccharopolyspora hirsuta          strains.                                                                       Agar medium                                                                              Determination                                                                          S. hirsuta ATCC 27875                                                                       S. hirsuta strain 367                           __________________________________________________________________________     Peptone-iron                                                                             S       Colorless (V)                                                                               Colorless or light tan                                                         wrinkled (V)                                              R       Pale yellow  Orange-tan                                                P        --          Pale tan to orange-tan                                    O       Melanin negative                                                                            Melanin negative                                Calcium malate                                                                           S       Trace white (A)                                                                             Trace gray (A)                                            R       Cream        Pale gray cream                                           P        --           --                                                       O       Malate solubilized                                                                          Malate slightly solubilized                     Glucose asparagine                                                                       S       Colorless to light tan (V)                                                                  Light tan (V)                                             R       Orange       Orange-tan                                                P       Orange       Orange-tan                                      Skim milk S       Tan (V)      Orange-brown (V)                                          R       Orange-tan   Dark orange-tan                                           P       Orange-tan   Deep orange-tan                                           O       Casein solubilized                                                                          Casein solubilized                              Tyrosine  S       Tan (V)      Orange-tan (V)                                            R       Orange       Orange                                                    P       Orange       Orange                                                    O       Tyrosine solubilized                                                                        Tyrosine solubilized                            Xanthine  S       Colorless (V)                                                                               Pale tan (V)                                              R       Pale yellow  Pale tan                                                  P       Pale yellow  Pale tan-peach                                            O       Xanthine solubilized                                                                        Xanthine solubilized                                              around growth                                                Nutrient starch                                                                          S       Colorless (V)                                                                               Pale tan (V)                                              R       Pale yellow  Pale tan                                                  P       Very pale yellow                                                                            Very pale tan                                             O       Starch hydrolyzed                                                                           Starch hydrolyzed                               Yeast extract-malt                                                                       S       Colorless (V)                                                                               Pale tan (V)                                    extract                                                                                  R       Orange       Pale orange-tan                                           P       Orange       Orange                                          Peptone-yeast                                                                            S       Colorless (V) with very                                                                     Colorless (V)                                   extract-iron      slight trace white (A)                                       (ISP-6)                                                                                  R       Yellow-tan   Light orange-tan to tan                                   O       Melanin negative                                                                            Melanin negative                                Tyrosine (ISP-7)                                                                         S       Trace white (A)                                                                             Very pale orange (V)                                      R       Yellow tan   Very pale orange                                          O       Melanin negative                                                                            Melanin negative                                Gelatin                                                                        Plain     S       Trace white (A) on                                                                          Colorless to pale yellow (V)                                      colorless surface                                                              pellicle                                                               P       None         None to trace pale yellow                                 O       Gelatin liquefied                                                                           Gelatin liquefied                               Nutrient  S       Trace white (A) on                                                                          Trace colorless (V) to trace                                      yellow (V) pellicle                                                                         white (A) on (V)                                          P       None         None                                                      O       Gelatin liquefied                                                                           Gelatin liquefied                               Broth                                                                          Synthetic nitrate                                                                        S       No surface growth                                                                           Trace white (A) on colorless (V)                          P       None         None                                                      O       Compact bottom growth                                                                       Compact to flocculent bottom                                      No reduction growth                                                                         No reduction                                    Nutrient nitrate                                                                         S       Trace white (A) on color-                                                                   Trace white (A) on colorless                                      less surface pellicle                                                                       surface ring                                              P       None         None                                                      O       Flocculent bottom growth;                                                                   Poor colorless compact bottom                                     No reduction growth; No reduction                            Litmus milk                                                                              S       Pale gray (A) on yellow-                                                                    Blue-gray surface ring                                            tan surface ring                                                       P       None         Deep red-tan                                              O       Litmus not reduced                                                                          Peptonization                                                     pH 6.7-7.3   pH 7.6-7.8                                      __________________________________________________________________________      S = Surface                                                                    O = Other characteristics                                                      R = Reverse                                                                    (V) = Vegetative Growth                                                        P = Pigment                                                                    (A) = Aerial growth                                                      

                                      TABLE 3                                      __________________________________________________________________________     Comparison of Saccharopolyspora hirsuta strains                                Tests       S. hirsuta strain 367                                                                     S. hirsuta ATCC 27875                                                                      S. hirsuta kobense ATCC                     __________________________________________________________________________                                        20501                                       Physiological Properties                                                       Temperature Growth from 18-45 C.                                                                      Growth from 25-45 C.                                                                       Growth from 18-45 C.                        Optimum Temperature                                                                        28-45 C.   37-40 C.    37-42 C.                                    Gelatin liquefaction                                                                       Complete   Positive at 27 C.                                                                          Positive at 27 C.                           Starch hydrolysis                                                                          Positive   Positive    Positive                                    Action on milk                                                                             No coagulation                                                                            No coagulation                                                                             No coagulation                                          Peptonization                                                                             Peptonization                                                                              Peptonization                               Melanoid pigment                                                                           Negative   Negative    Negative                                    production                                                                     Nitrate reduction                                                                          Negative   Negative    Positive                                    Carbon Source                                                                  Utilization                                                                    L-Arabinose ±       -           -                                           D-Xylose    ±       +           -                                           L-Rhamnose  -          +           -                                           D-Glucose   +          +           +                                           D-Fructose  ++         +           +                                           Sucrose     +          +           +                                           Raffinose   ++         +           +                                           Inositol    -          +           -                                           D-Mannitol  ++         +           +                                           __________________________________________________________________________

The compound of the invention process is produced when the elaborating organism is grown in an aqueous nutrient medium under submerged aerobic conditions. It is to be understood, also, that for the preparation of limited amounts surface cultures and bottles can be employed. The organism is grown in a nutrient medium containing a carbon source, for example, an assimilable carbohydrate, and a nitrogen source, for example, an assimilable nitrogen compound or proteinaceous material. Preferred carbon sources include glucose, brown sugar, sucrose, glycerol, starch, cornstarch, lactose, dextrin, molasses, and the like. Preferred nitrogen sources include cornsteep liquor, yeast, autolyzed brewer's yeast with milk solids, soybean meal, cottonseed meal, cornmeal, milk solids, pancreatic digest of casein, fish meal, distillers' solids, animal peptone liquors, meat and bone scraps, and the like. Combinations of these carbon and nitrogen sources can be used advantageously. Trace metals, for example, zinc, magnesium, manganese, cobalt, iron, and the like, need not be added to the fermentation media since tap water and unpurified ingredients are used as components of the medium prior to sterilization of the medium.

Production of the compound by the invention process can be effected at any temperature conducive to satisfactory growth of the microorganism, for example, between about 18° and 40° C., and preferably between about 20° and 28° C. Ordinarily, optimum production of the compound is obtained in about 3 to 15 days. The final pH of the fermentation is dependent, in part, on the buffers present, if any, and in part on the initial pH of the culture medium.

When growth is carried out in large vessels and tanks, it is preferable to use the vegetative form, rather than the spore form, of the microorganism for inoculation to avoid a pronounced lag in the production of the compound and the attendant inefficient utilization of the equipment. Accordingly, it is desirable to produce a vegetative inoculum in a nutrient broth culture by inoculating this broth culture with an aliquot from a soil, liquid N₂ agar plug, or a slant culture. When a young, active vegetative inoculum has thus been secured, it is transferred aseptically to large vessels or tanks. The medium in which the vegetative inoculum is produced can be the same as, or different from, that utilized for the production of the compound, so long as a good growth of the microorganism is obtained.

A variety of procedures can be employed in the isolation and purification of the compound produced by the subject invention from fermentation beers. Isolation can be accomplished by extraction with solvents such as methylene chloride, acetone, butanol, ethyl acetate and the like; and silica gel chromatography can be used to purify crude preparations of the antibiotic.

In a preferred recovery process, the compound produced by the subject process is recovered from the culture medium by separation of mycelia and undissolved solids by conventional means, such as by filtration or centrifugation, and solvent extraction of both mycelial cake or clarified broth. The clarified broth can be extracted with a suitable solvent, for example, methylene chloride (preferred), ethylacetate, butanol, and MIBK. The extract can be evaporated under reduced pressure to a concentrate and the antibiotic recovered from this cencentrate by subjecting the concentrate to chromatography over silica gel and eluting with methanol and methylene chloride.

The following examples are illustrative of the process of the invention, but are not to be construed as limiting. All percentages are by weight and all solvent mixture proportions are by volume unless otherwise noted.

EXAMPLE 1 Part A. Fermentation

A biologically pure culture Saccharopolyspora hirsuta strain 367, NRRL 12045, is used to inoculate 500-ml Erlenmeyer seed flasks containing 100 ml of sterile medium consisting of the following ingredients:

    ______________________________________                                         Glucose monohydrate     25 g/l                                                 Pharmamedia*            25 g/l                                                 Tap water q.s.          1 liter                                                ______________________________________                                          *Pharmamedia is an industrial grade of cottonseed flour produced by            Traders Oil Mill Company, Fort Worth, Texas.                             

The seed medium presterilization pH is 7.2. The seed inoculum is grown for three days at 28° C. on a Gump rotary shaker operating at 250 rpm and having a 21/2 inch stroke.

After three days incubation, the seed medium is used to inoculate (the inoculation rate is 5 ml of seed inoculum per 100 ml of fermentation medium) a series of 500-ml Erlenmeyer flasks containing sterile fermentation medium consisting of the following ingredients:

    ______________________________________                                         Glucose monohydrate     10 g/l                                                 Dextrin                 20 g/l                                                 Corn steep liquor       2.5 g/l                                                NH.sub.4 NO.sub.3       3.0 g/l                                                NaCl                    2.0 g/l                                                CaCO.sub.3              5.0 g/l                                                pH-7.2 (presterilization)                                                      ______________________________________                                    

The fermentation flasks are incubated at a temperature of 28° C. on a Gump rotary shaker operating at 250 rpm and having a 21/2 inch stroke. Harvest is usually after about 5 days of fermentation. A typical 5 day fermentation has the following titers of antibiotic in the fermentation broth:

    ______________________________________                                         Day             S. lutea Assay, Bu/ml                                          ______________________________________                                         2               8.0                                                            3               10.4                                                           4               10.4                                                           5               11.2                                                           ______________________________________                                    

In the assay results, a biounit (BU) is defined as the concentration of the antibiotic which gives a 20 mm zone of inhibition under the standard assay condition. Thus, if, for example, a fermentation beer has to be diluted 1/100 to give a 20 mm zone of inhibition, the potency of such beer is 100 Bu/ml.

B. Recovery and Purification

The whole beer (ca. 5,000 l) from a fermentation, as described above, is adjusted to pH 7.3 with NaOH and filtered on a 30 inch filter press using diatomaceous earth as a filter aid. During the filtration operation wash water is applied to the filter cake. From the filtration operation is recovered 5,500 l of clear fermentation browth which is then extracted twice with methylene chloride (1,400 l each time) to give a total of 2.800 l of solvent extract. This solvent extract is concentrated in vacuo to 10 l. Assay on a standard S. lutea disc plate assay gives a value of 2424 Bu/ml.

The extract concentrate described above (9 l), is chomatographed over a column containing 9 kg of silica gel (E. Merck-silica gel 7734). The column is eluted as follows:

20 liters methylene chloride; then 40 liters 2% methanol in methylene chloride; then 150 liters 5% methanol in methylene chloride; then 100 liters 10% methanol in methylene chloride. Four liter fractions are collected after an 80 liter forerun. Fractions 10-19 contain antibiotic U-59,761.

Cyrstalline antibiotic U-59,761 (41.4 g) is obtained on concentration of fractions 10-19. Another 12.8 g of crystalline antibiotic U-59,761 is obtained by chromatography of the mother liquors over silica gel with ethyl acetate as eluant. 

We claim:
 1. Antibiotic U-59,761, which is active against various microorganisms, and which in its essentially pure form has the following characteristics:(a) molecular weight of 422.2269 (mass spectrometry); (b) elemental analysis: C, 65.63; H, 7.97; (c) optical rotation: [α]_(D) ²⁵ =121° (c, +.7575 MeOH); (d) is soluble in methanol and ethanol; less soluble in methyl chloride and methylene chloride; and relatively insoluble in petroleum ether and cyclohexane; (e) a melting point of 201°-206° C.; (f) a characteristic infrared absorption spectrum when dissolved in a mineral oil mull as shown in FIG. 1 of the drawing; and (g) a characteristic 13C-NMR as shown in FIG. 2 of the drawing.
 2. A process for preparing antibiotic U-59,761 which comprises cultivating Saccharopolyspora hirsuta strain 367, having the identifying characteristics of NRRL 12045, in an aqueous nutrient medium under aerobic conditions until substantial antibiotic U-59,761 activity is imparted to said medium and recovering antibiotic U-59,761 from the medium.
 3. A process, according to claim 2, wherein said aqueous nutrient medium contains a source of assimilable carbohydrate and assimilable nitrogen.
 4. A process for recovering antibiotic U-59,761 from a fermentation beer containing antibiotic U-59,761 which comprises(a) filtering said fermentation beer to obtain clear fermentation broth; (b) extracting said clear broth with a suitable solvent for antibiotic U-59,761 to obtain a solvent extract containing said antibiotic; (c) concentrating said extract to a concentrate; (d) chromatographing said concentrate over silica gel; and recovering essentially pure antibiotic U-59,761 from said chromatography.
 5. A process, according to claim 4, wherein said fermentation beer is extracted with methylene chloride.
 6. A process, according to claim 4, wherein said chromatography column is eluted with methanol and methylene chloride. 